Perfluoroisopropylsulfur(iv) fluorides



3,170,954 1 PERFLUQRGHSQPROPYESULFURHV) FLUQREES Richard M. Rosenberg, .Wilnrington, I Deh, .assignor to E. I. du Pont de Nemours and Company, Wilmington, DeL, a corporation of Delaware No Drawing. Filed lune 16, 1961, Ser. Nor 117,513 12 flakes. Cl. 26$543) This invention relates to new organic-substituted sulfur fluorides and to a process for preparing these compounds. Some fluoroalkyl derivatives of higher valent sulfur fluorides, i.e., fluoroalkyl derivatives of sulfur tetrafluoride and sulfur hexafluoride, have become available through the energetic fluorination of materials such as carbon disulfide, alkyl sulfides or alkyl mercaptans. However, these fluorination processes primarily yield derivatives of sulfur heir'afiuoride and produce little or none of the corresponding derivatives of sulfurtetrafiuo'ride. Furthermore, up to now, only straight-chain PerfluoroalkylsulfurGV) fluorides have been obtained by such methods. V I

More recently,a process has appeared for the preparation of ,6-alkoxyperfluoroethylsulfur trifiuorides by reaction of sulfur tetrafluoride with alkyl trifluorovinyl ethers, but this process is specific to these others. Accordingly, new perflnoroisopropylsulfur(IV) fluorides are characfiuorides in which the sulfur is tetravalent.

It has now been discovered that previously unknown perfluoroisopropylsulfur(IV) fluorides can be prepared from perfluoropropylene and sulfur(lV) fluorides. The new perfluoroisopropylsulfur (TV) fluorides are characterized by the perfluoroisopropylsulfur group, in which the" sulfur is tetravalent and is bonded to 'at least two fluorine-atoms, the remain'ing sulfurvalence being satisfied'by'fluorine, a haloalkyl group, a fi-al koxyperfluoro ethyl group or an aryl group. r

a The compounds'of the invention are of the formula:

n v V CFa-IE SF2A- wherein A is fluorine, ,B-alkoxyperfluoroethyl of .up to 18 carbons,-aliphatically saturated aromatic hydrocarbyl of 6-18 carbons and up to 2 aromatic rings, or a-fiuorohaloalkyl of up to 18 carbons in which all halogens are of atomic number 9l-7 (chlorine and fluorine), i.e., the or fluoro atom may be the only halogen present,; any additional halogen being chlorine and/ or fluorine; The preferred compounds are those in which A. is fluorine, aromat-ic hydrocarbyl of 6-12 carbons or perfluoroalkyl of 1-12 carbons.

These perlluoroisopropylsulfurGV) fluorides are obtained by reacting perfiuoropropylene with a sulfurGV) fluoride of the formula ASF where A is defined as above, in the presence of cesium fluoride at a temperature of -0200" C. T he process is illustrated by the equation:

The mechanism of the above-illustrated reaction is unknown, but has been determined that the reaction does not take place in the absence of cesium fluoride tinderconditions hereinafter'described.

In the process of the invention, the reaction is accomplished at 0 to 200 C., e.g., in a closed reaction vessel United States Patent 7 3,170,954 1- Patented- Feni n-5 1965" procedure wherein the temperature held forshort periods of time at intermediate levels; This 's tepwiseheatf' ing procedure permits smooth operation and avoids sudden increase in the reaction pressurg 'butfsucha procedure is not necessary and the'reactants canQif'de sirefdfbe heated to the reactiontemperaturein a'singlefstepl The temperature of the reaction can be the range or Q to 200 C, though it ispr eferred 'touse a temperature in the range of 50 to 175 C., and'it is'especi'ally preferred to use 'a temperature in therange of 75 to 150 C. Althoughte'mperatures above ZOO C. can fbe used, it is advantageous not to exceed about'200" C. because of the onset of decomposition reactions that reduce yields and introduce contaminants.

Reaction pressure is not a critical factor in the process.

' It is most convenient to conduct the reaction under auto gfluoride and organosulfur trifiuorides in general arestrong-l 1y reactive with water.

and the tetravalent sulfur fluorides described'above, it is advantageous to use substantially anhydrous perfluoro propylene and cesium fluoride to avoid wasteful use of the sulfur fluoride raw materials and adventitious formation of undesirable by-products.

The molar proportions of the reactants are not critical since excess starting materials can be rec0vered.1 1nchanged. l-Iowever, in the reaction of perfluoropropylene;

his (perfluoroisopropyl) sulfur difluoride the relative proportions of the two products, p erfluoroisopropylsulfur trifiuoride and his (perfluoroisopropynsul fur 'difluoride, are subject to the law ofmass actioi1,i e.,

an excess of sulfur tetrafluoride will 'encourageformation' of'perfluoroisopropylsulfurtrifiuoride and an ex'cess of pe'rfluoropropylene will encourage formation of bis(perfluoroisopropyl) sulfur difiuoride. For economy'of opera-- tion, it -is preferred to use molar ratios of perfluoro-r propylene to the ASF reactant in therange of 5: lfto 'Isolationxand purification of the product isreadily accomplished by conventional procedures, e.g.,' byifrac tional distillation of the reactionmixture innn'eflicienf fractionating column. r v

The material of which the reaction vessel is constructed made of stainless steelgnickel molybdenum alloys.

-The invention is illustrated in greater detail' inthe following examples wherein the reactions were-"conducted under anhydrous conditions. Example I constitutes a preferred embodiment of the invention, I EXAMPLElfiwag. if

Pel'fluoroisopz'opylsulfur trifluoride and bis(per fluorois0pr0pyl)sulfur difluoride or, or, 1 "om-r Although the products of ,hy; drolysis do not affect the reaction of perfluoroprop'ylene,

A mixture of 60 g. (0.40 g. mole) of perfluoropropylene, 45 g. (0.42 g. mole) of sulfur tetrafluoride and 3.6 g. (0.024 g. mole) of anhydrous cesium fluoride was held under autogenous pressure in a 240 ml. pressure vessel, constructed of a nickel-iron-molybdenum alloy, at room temperature for 2 hours and was then heated at 100 C. for 2 hours and 150 C. for 10 hours. The mixture in the pressure vessel was cooled to C. and volatile material was removed at this temperature by vacuum transfer. Twenty grams of yellow, residual liquid remained in the pressure vessel.

Distillation of the volatile material yielded 30 g. of colorless liquid, B.P. 46 to 47 C., which was identified as perfluoroisopropylsulfur trifluoride by nuclear magnetic resonance and elemental analysis.

Analysis for C F S:

C S F Mo].

Calcd 14.0 12.4 73.6 258 Found 14.6 12.5 73.4 261 C S I F Calcd l5. 3 13. 6 64. 4 Found 15. 5 l4. 1 64. 5

The second fraction, which weighed 8.6 g. and boiled at 95 C. at 473 mm. pressure, was identified as bis(perfluoroisopropyDsulfur difluoride by nuclear magnetic resonance and elemental analysis.

Analysis for C F S:

C S F Calcd l7. 7 7. 85 74. 5 Found 1 7. 94 74. 6

Perfluoroisopropylsulfur trifiuoride is a colorless, voiatile liquid having a very penetrating odor and a toxicity similar tothat of phosgene. It is readily soluble in most of the common organic solvents, and it reacts vigorously with hydroxylated solvents such as ethanol. However, it is resistant to hydrolysis, showing negligible reaction with water in 45 minutes at room temperature and incomplete reaction in 24 hours. In the presence of a mutual solvent such as acetonitrile, the trifluoride reacts mildly with water to form the corresponding sulfinic acid (CF CFSO H Bis(perfiuoroisopropyl)sulfur difiuoride is a colorless, non-toxic liquid which is soluble in ether, acetone and chloroform but only slightly soluble or insoluble in ethanol, methylene chloride, acetonitrile, dimethyl sulfoxide and benzene. It is stable in air and is highly resistant to hydrolysis, showing no decomposition in boiling water and only minor reaction in aqueous KOH at 100 C.

" EXAMPLE .II

Perfluoroisopropylsulfur triflzroride and bis- (perfluoroisop opyl)sulfur difluoride FF; CFa CFs $F8 2CF;OF+SF4 CF JJFSF -kCF CFSF CF0E A mixture of 300 g. (2.0 g. mole) of perfiuoropropylene, 100 g. (0.93 g. mole) of sulfur tetrafluoride and 14 g. (0.092 g. mole) of anhydrous cesium fluoride, underautogenous pressure in a 1 liter pressure vessel constructed of a nickel-iron-molybdenum alloy, was heated at 100 C. for 5 hours and at 150 C. for 10 hours. The products of the reaction, isolated by the procedure described in Example I, were perfiuoroisopropylsulfur trifluoride (6.0 g., 2.5% conversion) and bis(perfiuoroisopropyl)sulfur difiuoride (314 g., 77% conversion).

A mixture of 24 g. (0.16 g. mole) of perfiuoropropylene, 25 g. (0.16 g. mole) of perfluoromethylsulfur trifluoride and 2.4 g. (0.016 g. mole) of anhydrous cesium fluoride, under autogenous pressure in an 80-ml. pressure vessel constructed of a nickel-iron-molybdenum alloy, was heated at C. for 3 hours and at 150 C. for 7 hours. The reaction vessel was cooled to 0 C. and gaseous products were vented at this temperature. Distillation of the liquid residue yielded 9.8 g. of clear, colorless product,.B.P. 707l C., which was identified as S-(perfluoromethyl)perfiuoroisopropylsulfur difluoride by nuclear magnetic resonance spectrum and elemental analysis. I

Analysis for C F S:

O S F S-(fi alkoxyperfluoroethyl)perfluoroisopropyl sulfur difluorides are readily prepared by substituting the appropriate ii-alkoxyperfluoroethylsulfur trifiuorides (prepared in the manner described in U.S. 2,928,870) for perfiuoromethylsulfur trifluoride in the process of Example Hi. Thus, when, e.g., pi-rnethoxyperfiuoroethylsulfur trifluoride, i l-propoxyperfluoroethylsulfur tritluoride, floctyloxyperiluoroethylsulfur trifiucride, fi-dodecyloxyperfiuoroethylsulfur trifiuoride or fi-hexadecyloxyperfiuoroethylsulfur trifiuoride, are reacted with perfiuoropropylene under the conditions recited in the above example, S-(fi methoxyperfluorethyl)perfiuoroisopropylsulfur difluoride, S-(,B-propoxyperfluoroethyl)perfluoroisopropylsulfur difiuoride, S-(fi-octyloxyperfiuoroethyl)perfiuorm isopropylsulfur difiuoride, S 8 dodecyloxyperfluoroethyl) perfiuoroisopropylsulfur difluoride or S-(B-hexadecyloxyperfluoroethyi)perfiuoroisopropylsulfur difluoride, respectively, are obtained in substantial quantities.

EXAMPLE IV S plzenyl perfl uoroisopropylsul fur di fluoride C F; 0 F3 OFQ F+CH5S F3 CF30 F S FgCaH5 A mixture of 15.0 g. (0.1 g. mole) of perfiuoropropylene, 16.6 g. (0.1 g. mole) of phenylsulfur trifluoride and 3.0 g. (0.02 g. mole) of anhydrous cesium fluoride, under autogenous pressure in a -ml. pressure vessel constructed of a nickel-iron-molybdenum alloy, was heated successively at 100 C. for 2 hours, at 125 C. for 2 hours, and at C. for 4 hours. A liquid product weighing 28.6 g. was obtained. Distillation of 12.0 g. of this liquid yielded 10.3 g. of colorless distillate, B.P. 4650 C./0.50.7 mm., which was identified as S- (phenyl)perfluoroisopropylsulfur difiuoride by infrared, ultraviolet and nuclear magnetic resonance spectra.

Analysis for C H F S:

Calcd. Found The sulfur(IV) fluorides used as starting materials in the above examples can be made by known methods: i.e., sulfur tetrafluoride is obtainable from sulfur, chlorine and an alkali metal fluoride by the method of assignees copending application Serial No. 798,828, now U.S. Patent No. 2,992,073; perfiuoromethylsulfur trifiuoride is obtainable from carbon disulfide and fluorine by the method of Tyczkowski and Bigelow, I. Am. Chem. Soc. 75, 3523 (1923); and phenylsulfur trifiuoride is obtainable from diphenyl disulfiide and silver difiuoride by the method of Sheppard, I. Am. Chem. Soc. 82, 4751 (1960).

Other sulfur(IV) fluorides, ASF which can be made by the above prior art processes and reacted with perfiuoroisopropylene by the process of the invention to produce S-(A)perfluoroisopropylsulfurdifluorides are as follows (the A portion of the reactant, and thus the product, are set forth in brackets following the respective reactants): fluoromethylsulfur trifiuoride [CH F], difluoromethylsulfur trifiuoride [CHF chlorodifluoromethylsulfur trifiuoride [CClF perfluorobutylsulfur trifiuoride [C F ot-fluoro-n-butylsulfur trifiuoride [CH (CH CHF], w-hydroperfluorooctylsulfur trifiuoride [CHF (CF perfluorododecylsulfur trifluoride [C F w-chloroperfluorododecylsultur trifiuoride [ClCF (CF perfiuorooctadecylsultur trifluoride [CF (CF p-tolylsulfur trifiuoride [p- CH C H p phenylphenylsulfur trifiuoride [p- C H C H 2,4-dipropylphenylsulfur trifiuoride [2,4- (CH CH CH C H Z-naphthylsulfur trifiuoride [2-C u and 2-(4,7-di-n-butylnaphthyDsulfur trifluoride [2-(4,7-[n-C H C H Perfiuoroisopropylsulfur(IV) fluorides described in the foregoing examples are surprisingly resistant to hydrolysis, a resistance which is especially strong in the disubstituted sulfur(IV) difluorides. The hydrolytic stability of perfluoroisopropylsulfur trifiuoride is unexpected, since organosulfur trifluorides ordinarily react readily with water, viz., perfluoromethylsulfur trifiuoride [Tyczkowski and Bigelow, J. Am. Chem. Soc. 75, 3523 (1953)], phenylsulfur trifiuoride [Sheppard, J. Am. Chem. Soc. 82, 4751 (1960)].

The tetravalent perfiuoroisopropylsultur fluorides are useful as ionic initiators for polymerization of cyclic ethers, e.g., polymerization of tetrahydrofuran occurs at room temperature in the presence of perfluoroisopropylsulfur trifiuoride and the resulting elastomeric product can be used as an adhesive. To illustrate, a clear solution of 10 drops of perfluoroisopropylsulfur trifiuoride in 1 ml. of tetrahydrofuran changed, in seventeen hours, to a gummy mass which was completely soluble in 2 ml. of warm tetrahydrofuran, forming a viscous solution from which an el-astomeric solid was precipitated by addition of water or methanol. Two glass plates, between which a few drops of the polymer solution were pressed and heated at 110 C. for minutes, were firmly bonded together when the assembly was cooled to room temperature.

The products are also useful as solvents. For example,

a 10% solution of low molecular weight tetrafiuoroethylene polymer in bis(perfluoroisopropyDsulfur difluoride was prepared. A piece of filter paper was soaked in the solution and was then dried. The treated paper was not wetted by water, whereas a similar untreated piece of paper was instantaneously wetted when dipped into water.

Since obvious modifications and equivalents in the invention will be evident to those skilled in the chemical arts, I propose to be bound solely by the appended claims.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A compound of the formula:

wherein A is of the group consisting of fluorine, a-fluoro haloalkyl of up to 18 carbons in which all halogens are of atomic number 9-17, fl-alkoxyperfluoroethyl of up to 18 carbons and aliphatically saturated aromatic hydrocarbyl of 6 to 18 carbons and up to 2 aromatic rings.

2. Perfiuoroisopropylsulfur trifiuoride.

3. Bis(perfluoroisopropyl)sulfur difluoride.

4. S-(perfiuoromethyl)perfluoroisopropylsulfur difluoride.

5. S-(phenyl)perfiuoroisopropylsultur difluoride.

6. A process of preparing perfluoroisopropylsulfur(IV) fluorides which comprises contacting perfluoropropylene with a sulfur(IV) fluoride of the formula ASF wherein A is of the group consisting of fluorine, a-fluorohaloalkyl of up to 18 carbons in which all halogens are of atomic number 9-17, fi-alkoxyperfluoroethyl of up to 18 carbons and aliphatically saturated aromatic hydrocarbyl of 6 to 18 carbons and up to 2 aromatic rings, in the presence of cesium fluoride, under anhydrous conditions and at a temperature of 0 200 C.

7. The process of claim 6 wherein the reactants are contacted under autogenous pressure at a temperature of 50175 C.

8. The process of claim 7 wherein the temperature is -150 C.

9. The process of claim 7 wherein the molar ratio of perfluoropropylene to ASF is in the range of 5:1 to 1:5.

10. The process of claim 7 wherein the sulfur(IV) fluo ride is sulfur tetrafluoride.

11. The process of claim 7 wherein the sulfur(IV) fluoride is perfluoromethylsulfur trifiuoride.

12. The process of claim 7 wherein the sulfur(lV) fluoride is phenylsulfur trifiuoride.

Houben-Weyl: Methoden der Organischen Chemie, vol. 5, part 3 (1962), pp. 84-95.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 5,170,954 February 23, 1965 Richard M. Rosenberg It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 1, lines 25 and Z6, strike out "perfluoroisopropylsulfurfl'v) fluorides are charac-fluorides" and insert instead methods are needed for making fluoroalkylsulfur fluorides line 54, for "0-0200 C." read 0-200 C.

column 4, line 34, for "perfluoroisopropylsulfur" read perfluoroisopropylsulfur Signed and sealed this 27th day of July 1965.

(SEAL) Attest:

ERNEST W. SWIDER' EDWARD J. BRENNER Attesting Officer Commissioner of Patents 

1. A COMPOUND OF THE FORMULA:
 6. A PROCESS OF PREPARING PERFLUOROISOPROPYLSULFUR(IV) FLUORIDES WHICH COMPRISES CONTACTING PERFLUOROPROPYLENE WITH A SULFUR(IV) FLUORIDE OF THE FORMULA ASF3, WHEREIN A IS OF THE GROUP CONSISTING OF FLUORINE, A-FLUOROHALOALKYL OF UP TO 18 CARBONS IN WHICH ALL HALOGENS ARE OF ATOMIC NUMBER 9-17, B-ALKOXYPERFLUOROETHYL OF UP TO 18 CARBONS AND ALIPHATICALLY SATURATED AROMATIC HYDROCARBYL OF 6 TO 18 CARBONS AND UP TO 2 AROMATIC RINGS, IN THE PRESENCE OF CESIUM FLUORIDE, UNDER ANHYDROUS CONDITIONS AND AT A TEMPERATURE OF 0-200*C. 